There are a variety of standards for integrated circuit (IC) cards, which can be mounted on mobile devices such as notebook personal computers (PC), personal digital assistants (PDA), digital video devices, digital cameras, and portable audio devices. These mobile devices will be referred to collectively as “host devices”. Recently, SD memory cards have been attracting attention because of their small size, high data transfer rates, and enhanced security features. For the purposes of this disclosure, the abbreviation “SD” stands for “secure digital” and various devices and their components related to this secure digital technology may be identified by the abbreviation “SD.”
At present, there are two international standards for SD-related devices: (1) the SD memory standard for memory devices, and (2) the SDIO standard for input/output devices (I/O). The SDIO standard is an extension of the SD memory card standard and covers input/output functions as well as memory functions. Card-shaped peripherals compliant with the SDIO standard are referred to as “SDIO cards.” An SDIO controller implements functions needed for peripherals to comply with the SDIO standard and connect to the host devices.
The “SDIO wireless communication card,” which contains the SDIO controller equipped with a Universal Asynchronous Receiver Transmitter (UART) interface and wireless communication capabilities compliant with Bluetooth, is known as a conventional technology for SD-related devices such as described in JP 2002-171303 A2 to Ito Takafumi. The SDIO wireless communication card is capable of communicating data from a host device, wirelessly via SDIO, to distant Bluetooth-compatible wireless communication devices.
SDIO is a relatively new standard in wireless technology. In view of this fact, future research and development must be conducted in such a way as to meet the specifications of the SDIO international standard. Because SDIO is a newly emerging technology, environments for SDIO-related design and development are not yet in place. Specifically, certain necessary hardware devices for SD interfaces and associated software are not presently available. For example, a converter between Personal Computer Memory Card International Association (PCMCIA) and SD interfaces is required for the existing wireless local area network (LAN) module equipped with a PCMCIA interface when developing an SDIO card provided with wireless LAN capabilities that is capable of mounting on host devices equipped with an SDIO slot. In another example, when developing an SDIO card with large-capacity and non-volatile memory functions, the SDIO card must be equipped with a memory interface which supports various types of memory.
In view of the above problems associated with the prior art, an object of the present invention is to improve the design for an SDIO controller and to develop environments for SDIO-related devices. Another objective in accordance with the present invention is to provide a highly versatile SDIO controller equipped with capabilities to interface an SDIO host with various applications (i.e., wireless operation, global positioning system (GPS) functions, memory, etc.) and to provide other devices benefiting from application of the SDIO controller.